Python Selenium wait for several elements to load

I have a list, which is dynamically loaded by AJAX. At first, while loading, it's code is like this:

<ul><li class="last"><a class="loading" href="#"><ins>&nbsp;</ins>Загрузка...</a></li></ul>

When the list is loaded, all of it li and a are changed. And it's always more than 1 li. Like this:

<ul class="ltr">
<li id="t_b_68" class="closed" rel="simple">
<a id="t_a_68" href="javascript:void(0)">Category 1</a>
</li>
<li id="t_b_64" class="closed" rel="simple">
<a id="t_a_64" href="javascript:void(0)">Category 2</a>
</li>
...

I need to check if list is loaded, so I check if it has several li.

So far I tried:

1) Custom waiting condition

class more_than_one(object):
    def __init__(self, selector):
        self.selector = selector

    def __call__(self, driver):
        elements = driver.find_elements_by_css_selector(self.selector)
        if len(elements) > 1:
            return True
        return False

...

try:
        query = WebDriverWait(driver, 30).until(more_than_one('li'))
    except:
        print "Bad crap"
    else:
        # Then load ready list

2) Custom function based on find_elements_by

def wait_for_several_elements(driver, selector, min_amount, limit=60):
    """
    This function provides awaiting of <min_amount> of elements found by <selector> with
    time limit = <limit>
    """
    step = 1   # in seconds; sleep for 500ms
    current_wait = 0
    while current_wait < limit:
        try:
            print "Waiting... " + str(current_wait)
            query = driver.find_elements_by_css_selector(selector)
            if len(query) > min_amount:
                print "Found!"
                return True
            else:
                time.sleep(step)
                current_wait += step
        except:
            time.sleep(step)
            current_wait += step

    return False

This doesn't work, because driver (current element passed to this function) gets lost in DOM. UL isn't changed but Selenium can't find it anymore for some reason.

3) Excplicit wait. This just sucks, because some lists are loaded instantly and some take 10+ secs to load. If I use this technique I have to wait max time every occurence, which is very bad for my case.

4) Also I can't wait for child element with XPATH correctly. This one just expects ul to appear.

try:
    print "Going to nested list..."
    #time.sleep(WAIT_TIME)
    query = WebDriverWait(driver, 30).until(EC.presence_of_element_located((By.XPATH, './/ul')))
    nested_list = child.find_element_by_css_selector('ul')

Please, tell me the right way to be sure, that several heir elements are loaded for specified element.

P.S. All this checks and searches should be relative to current element.

from Python Selenium wait for several elements to load